Chavez, 57, underwent an operation in Cuba on June 20 to remove a cancerous tumor in his pelvic area and received a first round of chemotherapy in mid-July.
Gripping a microphone, the vice president had a moment to shine as he stood in for President Hugo Chavez and welcomed hundreds of athletes to a competition hosted by Venezuela's government.
It was an embarrassing debut last month for 42-year-old Jaua just a day after Chavez delegated additional duties to him while undergoing cancer treatment.
Jaua, in fact, is typical of the faithful aides Chavez has chosen for his inner circle: loyal and inconspicuous, yet decidedly not charismatic and with none of the president's commanding verbal panache. "I'm a man of honor, steeped in the values of loyalty, friendship and principles, and I'm going to defend the constitutional mandate of President Chavez with my very life," Jaua told reporters recently.
Chavez, who has been undergoing a second round of chemotherapy in Cuba during the past week, has been praising Jaua and his Cabinet for stepping up their performance and pulling together.
Jaua has spoken with clarity and conviction in other appearances, and has enthusiastically stepped into the spotlight to promote Chavez's socialist views.
Jaua is often considered part of the "radical civilian wing" of Chavez's party, along with Foreign Minister Nicolas Maduro, a longtime ally who after working as a public transit union leader rose to become National Assembly president and eventually Chavez's top diplomat.
A recent survey by the Caracas-based polling firm Datanalisis found that behind Chavez, Jaua was the most popular figure within the president's movement. Chavez surprised many Venezuelans last month when he suddenly delegated some administrative duties to Jaua and his finance minister. While Chavez fights cancer, Jaua has presided over televised rallies in his place, and the president has sometimes called in to join him by phone from Cuba.
Jaua came from a family steeped in politics. After Chavez took office in 1999, Jaua was one of many Chavistas elected to an assembly that drafted a new constitution. A year later, Chavez made him private secretary.
Meanwhile, Chavez has said he will be relying on Jaua for more administrative help but that the vice president won't be called upon to stand in for him as a replacement, not even temporarily.
Historian Agustin Blanco Munoz put it bluntly by calling Jaua a loyal "puppet of Chavez" whose influence comes largely from the trust Chavez places in him.
"Jaua has none of his own characteristics of a leader," Blanco Munoz said.